Why won't datetime work for 0:00?

I have this code to help format a list of dates/times in a CSV file:

datfmt = '%s%s%s%s%f%s%s%s%d%s%f%s';
celldata = textscan(fid,datfmt,'Headerlines',1,'Delimiter',',');
dates = datetime(celldata{3});

When I try to write an output file using:

for iline = 1:length(dates)
    fprintf(fid,'%s\n',dates(iline));
end

the dates/times at the 0:00 mark don't read out with both the dates/times, only the dates (formatted differently than all the other values too). Why is this happening?

Answer 1

[Walter Roberson]

datetime('01/31/1983'), ans.Format

ans = datetime
   31-Jan-1983

ans = 'dd-MMM-uuuu'

datetime('01/31/1983 00:00'), ans.Format

ans = datetime
   31-Jan-1983

ans = 'dd-MMM-uuuu'

datetime('01/31/1983 17:45'), ans.Format

ans = datetime
   31-Jan-1983 17:45:00

ans = 'dd-MMM-uuuu HH:mm:ss'

What is happening is that when you do not supply a Format, the default format for time 00:00 is just the date without the time. If you want the time as well, specify a format specifically

datetime('01/31/1983 00:00', 'Format', 'dd-MMM-uuuu HH:mm:ss'), ans.Format

ans = datetime
   31-Jan-1983 00:00:00

ans = 'dd-MMM-uuuu HH:mm:ss'

[Peter Perkins]

Walter is right, but even MORE right would be to say, "CSV? use readtable, and tell it to read those timestamps directly into a datetime variable." textscan is not your friend.

Answer 2

[the cyclist]

It's not easy to debug this without seeing the data, but I would suggest explicitly adding a 'Format' Name-Value input to this line

dates = datetime(celldata{3});

so that that those dates are forced to include the time.